HC head conversion advice
 

I have initiated installation of a 6.1:1 head and have spent quite a few hours scrubbing scorched-on carbon off of the pistons faces, valves, and combustion areas. Apparently it was running far too rich for a long time before I bought the car.



Long story...but...the car was owned by my predecessor for less than a year and driven less than 250 km in that time. He admitted that he did zero maintenance at all over that period. (aaaaagh!!) He had the car from a friend who was unable to drive it due to health issues for three years prior...so it had been sitting for at least three years after a complete restoration and engine rebuild when it was rescued from a 47 year nap in a barn. It was a pretty good cosmetic restoration and even won a few awards at car shows (which are nowhere near as exacting as they are in the US). I asked about the GAV at the time of purchase and was told that it is the choke...and indeed, it was frozen in the full open position and only functioned as a choke. After learning what the GAV is supposed to do I managed to unfreeze it and make it functional. Still can't figure out how it was running at all in the full open position because I find that it runs best at about a quarter or half a turn. That could explain the extreme carbon build-up (black fuzzy plugs) after very few km driving. Now that I can run a leaner fuel mix I should expect less carbon build-up but...should I also be considering going to a hotter sparkplug with the new head? I am currently running the Champion W16Y plugs. Would the W18Y be a better idea? I have already installed the "Zipper" distributor with the "Flamethrower" hotter coil.



I am finding it best to do all of my own maintenance and upgrades after walking into my local classic car garage and catching the "Pre-war expert" mechanic hammering a stainless steel adapter piece into my cast iron exhaust manifold and having the cheek to try to charge me 300 Euro to weld the resulting crack shut. All he was asked to do was replace the manifold gasket and replace the brake linings!! Now I am in the market for a cast iron header because I do not trust welds on cast iron in high heat locations. This project of replacing the exhaust manifold with a header begs the question of going to a higher performance carb and an intake manifold that mates with the new header while not requiring adding a fuel pump. I suppose that pretty much requires keeping an up-draft carb...or? It needs to look convincingly authentic as German registration inspections are quite exacting for cars registered as "historic" and getting the reduced tax "H" license plates. As long as the header is cast iron nobody will notice. I even had to take out the LED headlight bulbs for inspection!


Any suggestions/comments will be appreciated.

Re: HC head conversion advice
 

IMO, the best way to removed carbon from the combustion chamber is to start the engine and run it till warn. Take a spray bottle and spray water into the intake till the engine falters but does not stop. Let it run for a short time further, then spray in more water till it stops. Leave it overnight and start it is the morning. The carbon will be blown out of the exhaust pipe.
The way this works is the carbon has been wet and time allowed for the water to soak into the carbon. When you start it next day, the high temperatures of the combustion chamber causes it to vaporise instantaneously, dislodging the deposits, like mini explosions.
Anybody who has had coolant leak into the cylinder while the engine is running, will have seen how clean the head it in that cylinder when they remove the head.

Re: HC head conversion advice
 

I agree with what Synchro said above - I watched an old experienced mechanic do this procedure back in 1969. A customer left an older car with him that ran pretty rough and apparently had a lot of miles on it, The mechanic did a complete tune-up; new points, plugs, condenser, adjusted timing, mixture, etc. and then put a piece of cardboard in front of the radiator and ran the engine until the temp was above the normal driving temp. He then took a Coke bottle and slowly poured water into the carb while holding the throttle open enough to keep the engine from dying. I couldn't believe the amount of carbon and debris that shot out of the tailpipe! After he did the water trick, he removed the cardboard while the engine was still running and let it cool down to normal temperature. I couldn't believe how smoothly that old engine ran!

Re: HC head conversion advice
 

A slight detour here: In your profile you state that your 1930 Tudor is a "three door". What is that? Photos?
M.

Re: HC head conversion advice
 

If you are so restricted on modifications, I suspect a B carburettor would not be noticed by a Government employee and it would give your car a lift.